The proposed research will address these important questions. It will build on the combined experiment of the Minnesota and Stanford programs to test the following major hypotheses: 1. A smoking prevention program which (i) corrects seventh graders' normative expectations for smoking, (ii) elicits a public commitment not to become a regular smoker, (iii) includes exercises for values clarification related to smoking, (iv) considers the mechanisms linking smoking to heart disease and cancer and (v) uses same age peer opinion leaders as intervention agents will be more effective in low risk schools than in high risk schools. 2. A smoking prevention program which (i) focuses on the short term physiological effects of smoking, (ii) reviews the evidence linking maternal smoking to fetal and infant health problems, (iii) trains students in decision making skills to cope with their numerous types of social problems. (iv) Examines environmental cues which elicit smoking and teaches self-management techniques to deal with such cues and (v) uses older peer leaders as intervention agents will be more effective in high risk schools than in low risk schools. 3. A program which is effective in deterring the onset of cigarette smoking in youth using; these techniques will also be effective in deterring the use of alcohol and marijuana, though no direct intervention activities for these substances are included.